French officials say 129 people were killed in Paris terrorist attacks claimed by the Islamic State (IS) extremist group.

Paris prosecutor Francois Molins said 352 people were injured in November 13 shootings and explosions in multiple locations in the French capital.

He added that 99 of the injured are in critical condition.

Molins also said seven "terrorists" – all wearing identical explosives belts – were killed in the attacks.

He added that three coordinated teams of gunmen struck at six different sites across Paris.

Molins said the type of explosives used by the attackers - who were wearing suicide vests - was triacetone triperoxide (TATP). TATP is a type of explosive that can be made with easily available chemicals and is difficult to detect.

The IS extremist group said in an official statement posted online November 14 that "eight brothers wearing explosive belts and carrying assault rifles" carried out the attacks.

It said the attacks were a response to insults to Islam's prophet and air strikes in "Islamic State territory."

The statement comes shortly after French President Francois Hollande said in a televised address that the attacks were committed by Islamic State extremists.

Calling the attacks an "act of war," Hollande said the attacks were planned and organized from abroad with help from inside France.

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The LA Times has quoted U.S. law enforcement officials with knowledge of the French investigation, as saying that the attack was seemingly planned in Belgium.

The newspaper wrote that the Paris attacks "apparently began with a small extremist cell in Brussels, where French authorities believe the attacks were planned and the operation financed."

German officials say a man arrested in Germany's southern state of Bavaria in early November after guns and explosives were found in his car may be linked to the Paris attacks.

"There are reasonable grounds for presuming that it might be related to the matter," Bavaria's state premier, Horst Seehofer, said on November 14.

At the scene of the worst carnage, the gunmen entered the Bataclan concert hall as it was hosting an American rock band and held dozens of the some 1,500 concertgoers there hostage as they went on a shooting spree.

Paris city officials told media that at least 89 people were killed in the concert hall.

Eyewitnesses present in the hall during the attacks said the gunmen, some shouting "God is greatest" in Arabic, systematically shot dead hostages as the music fans tried to hide.

Some victims were killed when the militants set off their suicide vests as the hall was stormed by elite French forces, who managed to shoot and kill one of the attackers before he set off his suicide bomb belt.

There was also an apparent double suicide bombing north of the center of the city near the Stade de France national stadium, where Germany and France were playing a friendly soccer match.

Meanwhile, people have been gathering around the world to mourn for the victims of attacks, holding candlelit vigils, singing the French national anthem, and leaving flowers and messages at French embassies across the globe.

National landmarks were lit up in the French Tricolore, including in Australia, China, the United States, and across many European cities.

​International Condemnation

World leaders are condemning the attacks.

U.S. President Barack Obama called the November 13 attacks "an attack on all of humanity and the universal values we share."

British Prime Minister David Cameron vowed that "we will do whatever we can to help."